[lwip-users] Using BOOTP with lwIP

[Amit Ashara]

Hello All,

I am trying to get BOOTP working with lwIP 1.4.1 stack. I am able to configure the device in STATIC IP address mode and send the BOOTP packet and have the BOOTP server send the BOOTP response. However the call back function for udp does not get invoked. After debugging the same, the issue seems to be in ip.c file. In the function ip_input

      if ((netif_is_up(netif)) && (!ip_addr_isany(&(netif->ip_addr)))) {
        /* unicast to this interface address? */
        if (ip_addr_cmp(&current_iphdr_dest, &(netif->ip_addr)) ||
            /* or broadcast on this interface network address? */
            ip_addr_isbroadcast(&current_iphdr_dest, netif)) {
          LWIP_DEBUGF(IP_DEBUG, ("ip_input: packet accepted on interface %c%c\n",
              netif->name[0], netif->name[1]));
          /* break out of for loop */
          break;
        }
#if LWIP_AUTOIP
        /* connections to link-local addresses must persist after changing
           the netif's address (RFC3927 ch. 1.9) */
        if ((netif->autoip != NULL) &&
            ip_addr_cmp(&current_iphdr_dest, &(netif->autoip->llipaddr))) {
          LWIP_DEBUGF(IP_DEBUG, ("ip_input: LLA packet accepted on interface %c%c\n",
              netif->name[0], netif->name[1]));
          /* break out of for loop */
          break;
        }
#endif /* LWIP_AUTOIP */

the check seems to fail at ip_addr_isany causing the netif pointer to be NULL and hence later in the code the udp stack call is not occuring. Since BOOTP requires the client to send the BOOTP request packet with IP address 0.0.0.0 the server responds to the IP address 0.0.0.0 which causes the check to fail. Is there some way I can bypass the same to get the BOOTP response to the application layer.

Furthermore: the same logic exists on lwip 2.0.2 so my assumption would be that it would not be possible with 2.0.2. I do understand that DHCP has superseded BOOTP, but legacy network still relies on the same.

Regards

Amit